Production and Distribution of Aldehyde and Alcohol Sex Pheromone Components in the Pheromone Gland of Females of the Moth Chloridea virescens

Abstract

Aldehydes are components of many moth sex pheromones, and are thought to be produced from analogous alcohols by oxidase(s) in the cell membrane or the gland cuticle. This implies that the two types of components are produced and/or stored in different parts of the gland: alcohols in cells and aldehydes in cuticle. Few studies have investigated the distribution of components in moth pheromone glands. Using rinse/extract sampling, stable isotope tracer/tracee methods, and decapitation/ pheromone biosynthesis activating neuropeptide stimulation, we studied production and distribution of (Z)-11-hexadecenal (Z11–16:Ald) and (Z)-hexadecenol (Z11–16:OH) in the gland of Chloridea virescens (formerly Heliothis virescens). The rinse, which likely sampled the surface and outer cuticle, contained large amounts of aldehyde and small amounts of alcohol. By contrast, the residual extract, which likely sampled cells and less solvent-accessible (inner) cuticle, had large amounts of alcohol and small amounts of aldehyde. When a tracer (U-13C-glucose) was fed to females, the aldehyde had higher isotopic enrichment than the alcohol in the rinse, but not in the residual extract, showing that in the rinse pool, Z11–16:Ald was, on average, synthesized before Z11–16:OH. This is consistent with greater aldehyde than alcohol flux through the cuticle. While our results are consistent with cell/cuticle synthesis sites for alcohol/aldehyde components, we cannot rule out both being synthesized in gland cells. We propose two alternative conceptual models for how site of production, cuticular transport and catabolism/metabolism might explain the relative masses of Z11–16:Ald and Z11–16:OH translocated to the pheromone gland surface in female C. virescens.

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Acknowledgments

We are grateful for funding of this work by a United States Department of Agriculture Hatch Project ND02388. We also thank the United States Department of Agriculture–National Institute of Food and Agriculture for an Instrument Grant, 2015-07238 contributing, in part, to the purchase of the GC/MS system.